1. Technical Field
The present invention relates to orthopedic surgery, and in particular to devices for stabilizing and fixing the bones and joints of the body. Particularly, the present invention relates to an instrument capable of reducing a spinal rod into position in a rod receiving notch in the head of a bone screw and holding the same in position and providing anti-torque effect on the bone screw while a bone screw locking cap is attached to the head of the bone screw.
2. Background Art
The spinal column is a complex system of bones and connective tissues that provides support for the human body and protection for the spinal cord and nerves. The adult spine is comprised of 24 vertebral bodies, which are subdivided into three areas including seven cervical vertebrae, 12 thoracic vertebrae and five lumbar vertebrae. Between each vertebral body is an intervertebral disc that cushions and dampens the various translational and rotational forces exerted on the spinal column.
There are various disorders, diseases and types of injury which the spinal column may experience in a lifetime. The problems may include but are not limited to scoliosis, kyphosis, excessive lordosis, spondylolisthesis, slipped or ruptured discs, degenerative disc disease, vertebral body fracture, and tumors. Persons suffering from any of the above conditions typically experience extreme or debilitating pain and often times diminished nerve function.
One of the more common solutions to any of the above mentioned conditions involves a surgical procedure known as spinal fusion. A spinal fusion procedure involves fusing two or more vertebral bodies in order to eliminate motion at the intervertebral disc or joint. To achieve this, natural or artificial bone, along with a spacing device, replaces part or all of the intervertebral disc to form a rigid column of bone, which is stabilized by mechanical hardware.
The mechanical hardware used to immobilize the spinal column typically involves a series of bone screws and metal rods or plates. When the spine surgery is posteriorly performed, it is common practice to place bone screws into the vertebral bodies and then connect a metal rod between the bone screws thus creating a rigid structure between adjacent vertebral bodies. When the spine surgery is performed anteriorly, it is common practice to attach a thin metal plate directly to the vertebral bodies and secure it to each vertebral level using one or more bone screws.
The process of properly inserting the spinal rod into the receiving slot of a bone screw and then securing that connecting rod in place often can require that the surgeon use a number of instruments and expend a great deal of time and effort to accomplish the task. When bone screws in several adjacent vertebra are to securely connected by a spinal rod, the repeated process of inserting the rod into the heads of the bone screws aid then securing the rod in place for each respective bone screw can be difficult, tiresome and time consuming. It is therefore important that an instrument be provided that is specifically designed to facilitate the process for the surgeon such that the connecting rod can be easily and quickly inserted into each bone screw and with minimal effort and loss of time. It is further important that the bone screws be held in a stable configuration to avoid the application of additional torque to the screw and the bone into which the screw is inserted when the locking cap is secured into position.
Conventional efforts to meet this need have fallen short in that no single instrument has been provided that effectively positions and inserts a connecting rod into position in the receiving slot of the head of a bone screw and also provides a stable anti-torque effect during the attachment of a bone screw locking cap to the head of each respective bone screw.
For these reasons there remains a need for a device which, in one simple action such as squeezing a lever, can reduce a posteriorly introduced rod into the head of a bone screw and provide an anti-torque effect to the bone screw while a bone screw locking cap is secured to the bone screw.